The present invention relates to a fiber array alignment arrangement and, more particularly, to a stacked array structure for securing a plurality of optical fibers in optical alignment with an associated microelectronic mirror switch (MEMS) arrangement.
Optical integrated circuits (OICs) are increasingly being used to implement optical devices including 1xc3x97N splitters, switches, wave division multiplexers (WDMs), and other optical devices, primarily due to the capability through optical device integration to obtain devices requiring relatively precise component configuration. Also, OICs generally have a more compact size and are more reliable and durable than discrete optical devices. One particular class of such OICs includes high-speed optical switches having a digital operating mode in which the apparatus rapidly switches a light beam. When used to switch a light beam between two optical paths, the high-speed optical switch can be used for generating a light beam having rapidly alternating wavelengths or spectral bands, primarily for the purpose of alternating or interleaving the excitation or illumination energy delivered to a target. In addition to alternating the spectral content of the light beam, the high-speed optical switch is also capable of operating as a shuttering system to cut off the light beam completely. Silicon-surface micromachining technology has been used to fabricate mirrors associated with such high-speed optical switches. In particular, optical microeletromechanical systems (MEMS) have been implemented with movable micro-mirrors.
Often, devices such as a MEMS optical switch are used in conjunction with an array of optical fibers external to the MEMS structure, that transmit optical signals to, and receive optical signals from, the MEMS optical switch. In its optimum arrangement, the MEMS switch is a two-dimensional array structure and requires accurate alignment of a two-dimensional fiber array to the MEMS substrate. In the past, separate fibers have been engaged in separate fiber ferrules, with the ferrules xe2x80x9cbundledxe2x80x9d together to form the fiber array. Such a fiber array arrangement is problematic in terms of expense, time spent forming the arrangement and, most importantly, the ability to provide accurate alignment of each separate fiber to an associated switch array element.
Thus, a need remains in the art for an improved technique for aligning an array of optical fibers to a structure such as a MEMS optical switch.
The need remaining in the prior art is addressed by the present invention, which relates to a fiber array alignment arrangement and, more particularly, to a stacked array structure for securing an a plurality of optical fibers in optical alignment with an associated microelectronic mirror switch (MEMS) arrangement.
In accordance with the present invention, a plurality of separate substrates are stacked to form a subassembly for supporting an array of optical fibers, where each substrate is formed to include an array of apertures for holding the fibers in place. In a preferred embodiment, each substrate comprises silicon which can be etched to form the array of apertures so that the fibers will be accurately aligned with the mirror elements on an associated MEMS arrangement. In accordance with the present invention, the xe2x80x9ctopxe2x80x9d silicon substrate of the stack can be further processed to including indentations aligned with the apertures for supporting a plurality of lens elements in alignment with the array of optical fibers.
In one embodiment of the present invention, alignment fiducials are formed on each substrate in the fiber array stack so as to provide both physical alignment between adjacent substrates (and, therefore, alignment of the fiber-supporting apertures), and a means of providing mechanical attachment between adjacent substrates.
In a preferred embodiment, one of the substrates may be processed to include a plurality of mechanical stops, each stop formed within an associated fiber aperture. The stop is used as a registration point for the endface of the associated fiber, thus ensuring that each fiber endface is properly located with respect to both its associated lens element and the MEMS arrangement.
It is an advantage of the present invention that the stack substrates may be formed utilizing any suitable material including, but not limited to, silicon, metal, an injection-molded or transfer-molded plastic.
Other and further advantages of the present invention will become apparent during the course of the following discussion and by reference to the accompanying drawings.